How does concentration affect chemical reactions?

Concentration can affect chemical reactions by increasing the reactant concentration. This will typically also increase the rate of reaction because a higher concentration of a reactant will cause more collisions in a specific period of time. In experiments involving two particles, for any reaction to occur those particles must collide. This is the case whether both particles are in solution or whether one is in solution and the other a solid. Thus, if the concentration is higher, the frequency of collisions is higher as well. It is important to note that when collisions happen, they do not always necessarily cause a reaction, as atoms can be misaligned or have insufficient energy. If the reaction only involves a single particle, the amount of collisions becomes insignificant. The energy of the molecules instead becomes a crucial factor, in addition to the concentration.